Expressions: The Visible Link

Darwin believed expressions of emotion reveal the unity of humans and their continuity with animals

He was an Englishman who went on a five-year voyage when he was young and then retired to a house in the country, not far from London. He wrote an account of his voyage, and then he wrote a book setting down his theory of evolution, based on a process he called natural selection, a theory that provided the foundation for modern biology. He was often ill and never left England again.

There's a lot more to Charles Darwin, however, than On the Origin of Species, the book that changed the world. For years I had the vague impression that Darwin must have written hundreds of books. He had published four volumes just on barnacles, I knew, but often it seemed that whenever I became interested in something, it would turn out that Mr. Darwin had written a book about it. It happened with worms (talk about "ecosystem services"); it happened with climbing vines moving through forests like green snakes; it happened with the extraordinary variety of flowers on a single plant species, including the purple loosestrife running amok in North America these days. And now it has happened on a question of interest to anyone who has ever lived with a dog or a cat: What do these creatures feel?

This year a new edition of The Expression of the Emotions in Man and Animals has appeared. In it Darwin wondered whether human facial expressions are innate, the same in cultures around the world. And in support of his underlying theory that humans are an extension of the animal continuum, he set out to show that animals have many of the same ways of physically expressing emotions as humans. The book was published in 1872. The current edition is the first to include all the changes Darwin wished to make.

Darwin didn't write hundreds of books, of course, but he covered extraordinary amounts of ground in those he did write. According to the editor of the new edition, Darwin wrote Expression to refute the contention that humans were created separately and are not on a continuum with the animals. More specifically, Darwin was writing against a book by a Sir Charles Bell who, for example, considered the muscle in the human face that "knits the eyebrows" to be uniquely human. In the margin of Bell's book, Darwin wrote: "monkey here? . . . I have seen well developed in monkeys . . . I suspect he never dissected monkey."

Darwin's primary goal was to show that all humans have certain innate qualities, including facial expressions. This, in turn, would be evidence of a common progenitor. His evidence was the sort that today would be dismissed as anecdotal. Yet Darwin compiled so much of it from so many correspondents in so many different places that its sheer volume and variety became authoritative. In Australia, for example, as related in a biography by Adrian Desmond and James Moore, "missionaries and magistrates from Queensland to Victoria ceased converting and incarcerating to observe aboriginal ways. . . ."

As Paul Ekman, the editor of this new edition, puts it, "He gathered information from others about people in different cultures, infants, children, the insane, the blind, and a variety of animals. No one writing about emotional expression today has used such diverse sources."

Darwin himself, of course, was a keen observer, whether of his own children, his dogs and cats, or even a stranger encountered on a train: "An old lady with a comfortable but absorbed expression sat nearby opposite me in a railway carriage. Whilst I was looking at her, I saw that the [muscles at the corner of the mouth] became very slightly, yet decidedly, contracted; but as her countenance remained as placid as ever, I reflected how meaningless was this contraction. . . . The thought had hardly occurred to me when I saw that her eyes suddenly became suffused with tears almost to overflowing, and her whole countenance fell."

The study of expression goes on today. Ekman, a professor of psychology at the University of California at San Francisco, has studied the expression of emotions for more than 30 years. His early work took him to a tribe in Papua New Guinea whose members had had almost no contact with the outside world. His translator would describe different situations and show them photographs of people with various expressions, and ask them to match situation with photograph. Almost invariably, they chose the same pictures as did people from countries around the world.

Darwin asked not only what humans and animals did, but why. He wound up with three principles he felt answered the last question. The first he called the principle of serviceable associated habits. By this he meant that certain actions could be of service in certain states of mind, and the same movements would be performed out of habit even when they had no use whatsoever. He offered pages of examples. A person describing a horrible sight will often close his eyes and even shake his head, as if to drive the sight away. Or a person trying to remember something, on the other hand, often raises her eyebrows, as if to see better.

By "expression" Darwin meant any bodily movement or posture ("body language"), not just facial expressions. He wrote of horses scratching themselves by nibbling those parts they can reach, and how horses show each other the parts they want scratched so they can nibble each other. A friend told Darwin that when he rubbed his horse's neck, the horse stuck its head out, uncovered its teeth and moved its jaws, just as if it were nibbling another horse's neck.

Darwin called his second principle antithesis. He described a dog ready to attack that suddenly recognizes its master and changes almost every aspect of its appearance. None of the latter expressions are of any use to the dog; they are simply the antithesis of what had been before.

Darwin offered his own study of how quickly a dog's expression can change: "I formerly possessed a large dog, who, like every other dog, was much pleased to go out walking. He showed his pleasure by trotting gravely before me with high steps, head much raised, moderately erected ears, and tail carried aloft but not stiffly. Not far from my house a path branches off to the right, leading to the hot-house, which I used often to visit for a few moments, to look at my experimental plants. This was always a great disappointment to the dog, as he did not know whether I should continue my walk; and the instantaneous and complete change of expression which came over him, as soon as my body swerved in the least towards the path was laughable. His look of dejection was known to every member of the family, and was called his hot-house face. This consisted in the head drooping much, the whole body sinking a little and remaining motionless; the ears and tail falling suddenly down, but the tail was by no means wagged."

His third principle has to do with involuntary actions of our nervous systems. He listed trembling brought on by fear or even delight, mentioning a boy so excited by having shot his first snipe that he could not reload for some time. Ekman quotes a present-day psychophysiologist as saying Darwin's emphasis on heart-brain communication "is now the focus of contemporary research and theory on both emotion and health."

So why was this book rejected or ignored for a hundred years? Ekman offers five reasons. First, Darwin was convinced that animals had emotions and expressed them. This theory was dismissed as anthropomorphism. Second, as mentioned above, his data was anecdotal. A third reason is that Darwin, a man of his times, believed that acquired characteristics could be inherited, an idea long since discredited. The fourth is that Darwin studiously avoided the communicative value of expressions. One possible explanation is that he was steering clear of the idea, common in his day, that God had given humans special physical capabilities to form expressions. The last brings us right up to the current controversy over such ideas as sociobiology. In Darwin's day behaviorism ruled. People believed that we are completely products of our environment, and therefore that "equal opportunity would create men and women who were the same in all respects." Most scientists today agree that we are creatures of nature as well as nurture. Genetics, not culture, makes certain expressions universal.

This is a book you'd want to have in your cottage the year it rained every day. It also is a book that leaves you staring into space, wondering what might have been if this sickly recluse had felt a little stronger during the last 40 years of his life.